This invention relates generally to laser devices and more particularly to laser scanning apparatus.
Laser scanning apparatus for use at checkout counters in supermarkets and other retail establishments are gaining wider and wider acceptance. Such devices are generally mounted within the counter and have a window at the top thereof through which a scanning pattern is projected. The scanning pattern is created by a laser and associated optical components which produce plural scan lines which intersect in various patterns. A bar code, such as the Uniform Product Code, which is imprinted on the packaging of a product is then brought into the field of the scan pattern so that the scan pattern traverses the bar code. Light reflected off the bar code is received back through the window of the scanning device by optical means and associated decoding means to provide signals indicative of the bar code. These signals can be utilized to identify the article bearing the code and provide pricing information.
In order to ensure that there are sufficient lines in the pattern to ensure that all of the bar code is traversed, thereby ensuring that the code is read accurately, prior art devices have utilized various optical configurations including mirrors, prisms, and the like to fold the beam and create complex patterns, such as comb patterns, orthogonal patterns, interlaced patterns, star-like patterns, etc.
For example, in U.S. Pat. No. 3,902,048 (Fleisher et al.) there is disclosed an omnidirectional laser bar-code scanner for use in check-out counters. That device creates a plurality of interlaced scan lines extending in differing directions. The means for producing that pattern consists of a laser which projects a beam of light onto a multifaceted mirror which is rotated about a horizontal axis to deflect the light beam vertically into a mirror tunnel assembly disposed thereabove.
In U.S. Pat. No. 3,928,759 (Sansome) there is disclosed a laser scanner for omnidirectional reading of bar codes. The pattern consists of a longitudinally extending line and a set of lines perpendicular thereto to create a comb-like pattern. The pattern is created by use of a laser tube which projects a beam of light into a beam splitter. One of the beams is projeted via angled mirrors to a horizontally rotating multifaceted mirror to produce the horizontal line of the pattern. The other beam is projected off an angularly mounted rotating mirror to cause the beam to sweep axially along the multifaceted mirror to produce the plural perpendicularly extending lines of the pattern.
In U.S. Pat. No. 4,006,343 (Izura et al.) there is disclosed a laser scanner for projecting an x-shaped or intersecting scanning pattern through a corresponding shaped window on a check-out counter. The pattern is created by splitting a laser beam, produced by a horizontally disposed laser tube, into two beams. One beam is projected into a first angled deflecting mirror which rotates about a first horizontal axis to cause the beam to project upward to sweep across the window in one direction. The other beam is projected into a second angled deflecting mirror, which rotates about another horizontal axis but perpendicular to the first axis, to project the beam upward and to sweep it across the window perpendicularly to the first sweep.
While the foregoing patented devices, as well as commercially available omnidirectional laser scanners, may be generally suitable for their intended purposes, such devices have been necessarily large and bulky. Accordingly, such devices necessarily project a considerable distance below the top of the counter while also taking up a substantial portion of the space below the counter.